Solvent and process of treating mineral oils



Patented Mar. 7, 1939 PATENT OFFICE SOLVENT AND PROCESS TREATING MINERAL OILS Q Malcolm H. Tuttle, New Rochelle, N. Y., assignoi' to Max B. Miller & 00., Inc., New York, N. Y., a corporation of Delaware 7N0 Drawing. Application June 27, 1935, Serial 7 No. 28,673. Renewed November 4, 1937.

Great Britain October 22, 1934 '7 Claims.

This invention. relates to improvements in the extraction of mineral oils as .set forth in United States .Letters Patent No. 1,912,349, issued .to Malcolm H. Tuttle, May 30, 1933, and to which reference is hereby made for the purpose of amplifying the present disclosure, if need be. This application is a continuation in part of my copending application, Serial No. 673,179, filed May 27, 1933.-

. .As set forthin said patent, when cresylic acid is employed in conjunction with a paraflinic solvent for refining mineral oils, it is an excellent solvent. However, additional improved results may. be achieved in accordance with the present invention...

' ,A feature of. the present invention therefore resides in the provision of an improved process, of.the.character described in said patent, this process-involving a superior naphthenic solvent mixture comprising about 18 to 38% phenol, about "77 to 57%. cresols (ortho, meta and 'para in any usual relative. proportions) and preferably, though not necessarily,. about 5% of the higher boiling homologues of pyridine (boiling points? about 365 F. tol405 F.) as found in coal tar. If desired, other cresylic compounds, e. g., wood tar homologues of cresols, such as guaiacol, creosol and/or Beechwood creosote (which contains large amounts of such homologues) may be employed in place of all or part of the cresols, such compounds being even superior to cresols in many respects. For instance, comparable and even improved results may be achieved with relatively small actual amounts of these solvents.

I have found that such solvents are especially advantageous where used in conjunction with paraffinic solvents, such as liquefied normally gaseous hydrocarbons like propane or mixtures of the same with ethane or butane, or such as petroleum ether (largely hexane), and when so employed produce superior results with most if not all mineral oil stocks to be treated.

By way of example, when 2 parts by weight of a naphthenic solvent of the type set forth above are mixed. with equal weight of petroleum ether and 1 part by weight of a residual oil stock, such as Mid-Continent crude oil from which the lighter fractions including gasoline and kerosene have been removed by distillation, and the mixture is allowed to separate into layers at about 55-65 F., a good quality and high yield of lubricating oil may be produced upon separating the upper layer and removing the solvents therefrom. Preferably, the paraflinic and naphthenic solvents are introduced to an extraction system at spaced points and are counterflowed with respect to one another, the charge oil being introduced between these points and the upper and lower layers thus formed being removed, the upper, or raffinate or parafiinic layer being removed adjacent the point at which substantial naphthenic solvent is introduced and the lower, or extract or naphthenic layer being removed adjacent the point at which substantial paraffinic solvent is introduced. An example of such a system is illustrated in my patent to which reference has been made.

A particular advantage of the present process is that it can be efficiently carried out at normal temperatures :without the use of excessive amounts of solvents and without the addition of outside heat or cold to the extraction chamber or chambers of the system. It will be understood, however, that where the solvents are recovered from the removed layers by evaporation, some heat may be imparted to the oil when these solvents are returned to the system, so that if the temperature of extraction is somewhat above air temperatures prevailing at the plant, the recovered solvents can be reintroduced without excessive cooling and while still warm. The properties of the solvents and other conditions may vary somewhat depending upon the character of the oil treated-for instance, the source of the stock and whether it is a residue, distillate or other fraction.

Accordingly, although cresylic acid (as the term is understood in the art unless chemically pure is specified) may contain appreciable or substantial phenol, often a few percent, and is an excellent solvent, I have found that novel and improved results may be achieved according to this invention when rather high or additional amounts of phenol are used, since the critical solution temperature (below which the solvents and oil separate into layers) is thus regulated, and the operating temperatures (which are advantageously not greatly below the critical solution temperature) may accordingly be controlled at substantially ordinary temperatures (say 55 F. to 65 F. for petroleum ether and 70 F. to 90 for propane, in the proportions mentioned), Specifically, increases in the phenol content have the effect of raising the critical solution temperature, and hence the desired operating temperature, over those for cresylic acid containing the more usual or lower percentages of phenol. At the same time, within the approximate ranges mentioned the phenol is not present in so large a proportion as to produce the undesirable results attributable to phenol alone or to the presence of too large a proportion of the same. Moreover, a high yield of good oil is thus produced, the raflinate oil, after recovery of solvents, being an excellent grade of lubricating oil. Also, the presence of some water in the stock is not markedly troublesome when pyridine or pyridine homologues are present in substantial amount. Then, too, the pyridine homologues appear to increase the solubility of oil in the phenol-cresol mixture, and their presence is therefore desirable though not in all cases essential. Similarly, by adding a limited solvent such as aniline in amount of about 8-15%, or furfural in amount of about 15-25%, to cresylic acid or the like, the critical solution temperature may be raised to a point that the extraction of the oil under treatment may be carried out at ordinary room temperatures without substantial cooling of the materials in the system and without introducing a heating step in said system.

The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described, or portions thereof, but it is recognized that various modifications are possible Within the scope of the invention claimed.

I claim:

1. Process of separating a mineral oil into paraffinic-type and naphthenic-type fractions which comprises treating the oil jointly with a parafiinic solvent such as a liquefied normally gaseous hydrocarbon and with a naphthenic solvent containing about 18-38% phenol, and about 77-57% cresylic substances under conditions adapted to cause the oil to separate into layers, separating the layers and recovering the solvents therefrom.

2. Process according to claim 1 wherein the naphthenic solvent contains about of the higher boiling homologues of pyridine.

3. Process of separating a mineral oil into parafiinic-type and naphthenic-type fractions which comprises treating the oil jointly with a parafiinic solvent such as a liquefied normally gaseous hydrocarbon and with a naphthenic solvent containing about 18-38% phenol, and about 77-57% cresylic substances under conditions adapted to cause the oil to separate into layers, the solvents being counterfiowed and the oil being introduced to the solvents at a point between the points at which the solvents are introduced, separating the layers and recovering the solvents therefrom.

4. Process in accordance with claim 1, wherein at least a portion of said cresylic substances are wood tar compounds of the group consisting of guaiacol, cresol and Beechwood creosote.

5. Process of extracting a mineral oil which comprises treating said oil jointly with a paraffinic solvent and with a naphthenic solvent composed primarily of cresylic substances and containing sufiicient amounts of phenol to permit the extraction to be conducted without the addition of extraneous cold to the mixture under extraction, enabling the mixture to separate into layers, and separating the layers.

6. Process of extracting a mineral oil which comprises intermingling the oil with a parafiinic solvent and with a naphthenic solvent mixture comprising a naphthenic solvent having the solvent power of cresol for naphthenic oil constituents and having a low miscibility temperature with said paraffinic solvent and oil, and a naphthenic solvent having a relatively limited solvent power for naphthenic oil constituents and having a relatively high miscibility temperature with said paraffinic solvent and oil, said naphthenic solvents being employed in such proportions as to enable the mixture to separate into layers at ordinary room temperatures, separating the layers thus produced, and separating the solvents from said layers.

7. Process according to claim 6, wherein said limited solvent is one of the group consisting of aniline and furfural.

MALCOLM H. TU'I'I'LE. 

